Some heavy vehicles, of which tractor-scrapers are an example, have an oil reservoir in a location which is so inaccessible that an operator is likely to neglect checking the oil level as frequently as he should. The oil reservoir for the transmission-differential of a powered scraper of a tractor-scraper is particularly difficult from this point of view.
A typical vehicle oil reservoir is provided with a dip stick type of gauge which is carried in a tube and has its lower end in the reservoir. In order to determine the level of oil in the reservoir it is necessary to remove the dip stick, wipe it clean, reinsert it, and see where the oil level is on the stick. This is easy with most vehicles, but in certain types of vehicles the reservoir is so located that to check the oil level with the dip stick is quite difficult. Obviously, the oil reservoir for a vehicle crank case or transmission-differential must be somewhere in the bottom of the vehicle; and while it is simple enough to extend a filler pipe from the reservoir to a convenient location for adding oil, the top of a dip stick cannot always be as conveniently located because it must be in a pretty straight line from the lower portion of the reservoir.